The heating system of the Roman baths used hot air and convection currents. The Romans helped pioneer the idea of central heating. This invention comes in useful for soldiers or Roman officials sent to patrol or maintain the Pax Romana in the most northern point of the Empire. The Romans were certainly able to build many of their more unusual buildings because of their rather useful invention of concrete, which is still one of the most useful of all building materials. Following the Romans’ example the British government built many blocks of flats in the 1960’s and 1970’s to accommodate the increased populations in the inner-city areas of our country. Central heating in the modern world still operates on the same principles of circulating hot air and water. The Romans were easily able to adapt their building materials and styles to create that most Roman of creations, the mosaic.